Pressure-medium operated percussion or impact apparatus

ABSTRACT

A rock drill having a reciprocating piston in a cylinder for striking the drill rod when pressure medium is supplied to alternate sides of the piston, with the piston and cylinder having grooves which on relative rotation of piston and cylinder convey pressure medium to one side or the other of the piston.

D United States Patent 1 1111 3,747,694 Kollandsrud 1 July 24, 1973 [541 PRESSURE-MEDIUM OPERATED 3,453,657 7/1969 Bolton et a1. 173/136 PERCUSSION 0 IMPACT APPARATUS 3,616,865 11/1971 Sudnishnikov et al 173/137 3,692,122 9/1972 Cunington 1. 173/136 [75] Inventor: Per Kollandsrud, Ljan, Norway 73 A A S M l B M l N 1 sslgnee van M v orway Primary Examiner-James A. Leppink 1 Flled! 1971 Attorney--Holman & Stern [21] Appl. No.: 204,607

[30] Foreign Application Priority Data [57] ABSTRACT Dec. 7, 1970 Norway 4686/70 A rock drill having a reciprocating piston in a cylinder [52] US. Cl. 173/137, 173/105 for striking the drill rod when pressure medium is sup- [51] Int. Cl B2511 9/00 plied to alternate sides of the piston, with the piston [58] Field of Search 173/105, 134-138 and cylinder having grooves which on relative rotation of piston and cylinder convey pressure medium to one [56] a References Cited side or the other of the piston.

1 "UNITED STATES PATENTS 3,480,088 11/1969 Ghelfi 173/136 4 Claims, 7 Drawing Figures PATEmEnJuLemra SHEET 1 2 BF 3 BACKGROUND OF THE INVENTION The present invention relates to a pressure medium operated percussion or impact apparatus where a valveless arrangement is to control the axial movement in the apparatus which may be, for example, a rock drilling machine in which a working piston must execute rapid axial movements in a cylinder between one reversing position on the tool side and one reversing position at a distance from the tool.

It is frequently the case that such tools must also execute rotary movements, for example, inrock drilling machines in order that the cutters on the drill crown shall attack the rockin a new position between each stroke. The invention is particularly expedient for such purposes, but is not solely restricted thereto. It can also be used when the tool is to have a percussive or vibratory movement without rotation, for example, if the tool is a pick in a frozen earth breaker or the hammer weight in a shorewall or pile driving unit. I

The invention can also be used in an apparatus without special tools, for example, by utilizing the vibration occuring in the actual cylinder.

By forming the lwork piston with great inertia in relation to the cylinder, the piston can work freely and the vibrations inthecylinder may be utilized instead, for example, for soil compression etc.

Such percussion and impact mechanisms have usually been driven by means of compressed air with 6 7 kp/cm pressure. On compression of the air, a substantial partof the energy produced is lost in heat. Great energy loss occurs also in the actual working machine so that the degree ofeffectivity of a conventional rock drilling machine driven by compressed air is below 20 percent, as a general rule. Other problems arising are high level of noise, condensate and frost problems, conditions which are much less unfavorable with operation by oil under pressure.

PRIOR TECHNIQUES In recent years, there has been a rapid development of components for transference of effect with oil under pressure in the range of 100 300 kp/cm, inter alia, for piston movements in a number of work machines. The energy transference to rotory movement can also take place with a substantially greater degree of effectivity thanwith compressed air. Itis thus obvious to use operation with oil under pressure in rock drilling machines, inter alia, by reason of the much greater degree of effectivity achieved.

Several attempts at this have been made, of for example, Norwegian Pat. Nos; 98.724, 99.065, 100.622, 110.602 and 117.234. 3

In rock drilling machines, for example, highstroke frequency is required, from about 2,000 strokes per minute and upwards. This necessitates rapid reversal of the supply and return connections for the liquid flow to the top and bottom of the piston. In previously known The invention is further described hereinafter with reference to the drawings where:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view partly in elevation and partly crosssection of an embodiment of the invention,

FIGS. 2-4 are views similar to FIG. 1 of further embodiments,

FIG. 5 is a view in cross-section ofthe locking mechanism in FIG. 4,

FIG. 6 is aview similar to FIG. llofyet a further embodiment, and

. FIG. 7 is a view in cross-section through the cylinder and piston of the inlet and outlet channels, the view.

being on an enlarged scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS FIG. 1 shows an embodiment of the invention for percussion drilling machine, that is to say that the workingpiston, the drill. rod and. drill bit are rigidly connected so that the drill bit is lifted clear of the bottom of the drill hole between each working stroke whereafter it strikes the bottom with great force.

The construction consists of a rotary motor. 1. with a supply channel-A and an outlet channelB for the drive medium. The rotary motor canpreferably be constructed for hydraulic operation, but may also be driven by means of compressed air or electricity. To

outgoing shaft 2 of the motor, a coupling sleeve 3 is rig idly connected. This is .provided with longitudinal grooves toward a working piston 4 which has opposing grooves so that the piston is forced to rotate at the same speed, but with free axial movement. The workingpiston 4 has two tapered throats 5 and 6 on either side of a portion 7 of greater diameter. A cylinder 8 encloses the piston so that annular working chambers 9 and 10 are provided on either side of the piston 7. The piston is further provided with longitudinal grooves 11 and 12 for the pressure medium. Every other groove opens to the annular chambers 9 and 10. In the cylinder, a-channel C is further provided for supply of pressure medium and a channel D for the outlet. The channels are located with respect to the grooves in such a manner that, when the supply channel C via groove 11 is in communication with a chamber 9 at the topside thereof, the bottom chamber 10 via the channel 12 is in communication with the outlet channel D. The cylindrical portion of the piston fits tightly in the cylinder and prevents direct overflow. The oil under pressure in the annular chamber 9 will thereby drive the piston with great force. On rotation of the piston with the rotary motor 1, the communicationswill be reversed so that the annular chamber 10 is under pressure and chamber 9 is connected to the outlet conduit whereby the piston is drive medium, that suitable stroke length is achievedbetween each reversal of the direction offorce onthe piston. I t i The cylinder is further provided with an inlet channel E for scavenging water or scavenging compressed air.

The cylinderopens intoan annular chamber 42 which,

via a bore 43in-the piston, is in communication with a central bore through a connecting sleeve 13, a drill rod 14 and a drill bit 15. The drilling dust is thereby scavenged in a direction away from the bit and out of the drill hole.

FIG. 2 shows a second embodiment example for impact drilling, that is to say that the working piston is not rigidly connected to the drill rod, but instead strikes on the drill rod. A piston 16 is here provided with a central bore 'for a separate shaft 17 which, via longitudinal grooves 18 and 19, transfers the rotation to a neckadapter 20 which, in a corresponding manner as in FIG. 1 is connected to the drill rod and bit. The rotary motor rotates thereby both the working piston 16 and the drill bit. Instead of raising the entire drill rod between each impact, only the piston 16 is raised. At the termination of the working stroke, the piston strikes with great force against the neck-adapter whereby the energy is transmitted as a pressure wave through the drill rod to the bit.

FIG. 3 shows a third embodiment example having two rotary motors. Motor 21 rotates only the piston; a separate motor 22 driving, via gearwheel 23 and intermediate wheel 24, a gearwheel 25 on a neck-adapter 26. The speed of rotation may here be adjusted independently of the stroke frequency. Otherwise the effect is as described hereinabove.

FIG. 4 shows a further embodiment example of the invention where the rotary motor is replaced by a locking mechanism. The working piston is provided here with, in part, right-hand grooves 28 in engagement with a locking wheel 30 and, in part, left-hand grooves 29 in engagement a locking wheel 31. Both the locking wheels are adapted freely to rotate in one direction of rotation, but are locked against the opposite direction by locks 32 and 33. FIG. shows a section with the locking mechanism seen from above.

On supply of pressure medium, piston 27 is pressed in direction toward the drill bit. The locks 32 thereby lock the locking wheel 30 while the locks 33 permit the locking wheel 31 to rotate freely. When the piston arrives in a lower reversing position, it is rotated to the extent that the oil conduits are reversed so that the piston is forced to return. Locks 33 are thereby actuated and lock the locking wheel 31, with the locking wheel 30 being now freely rotatable.

The piston is also provided here with straight grooves 35 which are in engagement with opposing grooves in a neck-adapter 34. The drill rod and drill bit are thereby forced to rotate.

FIG. 6 shows an even further embodiment example which externally is similar to FIG. 1, but in which a piston 36 has grooves only to annular chamber 37 while annular chamber 38, through a separate channel 39, is in communication with the inlet conduit. Further, piston throat 40 is of substantially less diameter than throat 41. The axial force on the piston from the annular chamber 37 is thereby greater than that from chamber 38 and, in the illustrated position, the piston will be pressed in the direction of the drill bit even though both chambers are under pressure. On further rotation of the piston, the communication between the inletchannel and the annular chamber 37 is closed. The annular chamber 37 is connected instead with the outlet channel, the pressure in chamber 37 is released, and the piston is pressed back by the continuous pressure in chamber 38, and the entire cycle is repeated. If the annular surface on the piston in the chamber 37 is double the surface in the chamber 38, the axial force is equal in both ways, however, other conditions may be of interest in the same way that the annular chambers from the previously mentioned embodiments do not have to be equal. A disadvantage of the embodiment according to FIG. 6 with respect to previous embodiments is that the return oil flow becomes more pulsative.

Further alternatives may be envisaged, for example,

locked shaft rotation for the working piston as illustrated on FIG. 4 combined with separate rotary motor for the drill rod as illustrated on FIG. 3.

Common to all alternatives is the importance of greater cross-section in the oil channels and choke loss in the rapid reversals in the oil flow may be mode-rate.

FIG. 7 shows a section in larger scale the through cylinder and piston at the inlet and outlet channels. In place of an inlet channel and an outlet channel, there are, in cylinder 42; nine inlet channels 43 which, via branches (not shown), are in communication with the inlet conduit, and also nine outlet channels 44 with connection channels (not shown) for a common return conduit. A piston 45 is provided with eighteen longitudinal grooves, every other groove having communication to the bottom and top side. Nine working cycles are thereby provided for each rotation, that is to say at, for example, 300 rpm; 2,700 strokes per minute. In that the oil flow when passing out and in from cylinder to piston is split into nine courses, the speed and thereby the loss of effect in the drive medium is moderate. Various numbers of channels may be expedient depending, inter alia, on the size of the machine.

In order to even out the pulsation in the liquid flow, the supply and outlet conduits respectively may be provided with accumulators. These may be either built into the actual drilling machine or may be located in the conduits at some distance therefrom. Furthermore, the hydraulic unit should be provided with valves forstarting and stopping; prevention of over-pressure when, for example, the drill is wedged fast, the filter is clogged etc., which are outside the scope of the present invention.

A good hydraulic oil is preferably used as pressure medium, however, oil-water emulsions, pure pressure water or other liquids can also be envisaged for use where this is expedient.

I claim:

1. A pressure medium-driven or impact apparatus including a cylinder, a working piston in said cylinder, means for supplying pressure to the piston, in which by supply of pressure to alternating sides of the piston the piston is caused to reciprocate, means to rotate the piston, the piston and cylinder being provided with channels which, on rotory movement of the piston relative to the cylinder, open and close the pressure medium channels, with the channels opening at the top and bottom side of the piston respectively.

2. The pressure medium-driven percussion and impact apparatus as claimed in claim 1, in which a motor constitutes the means to rotate the piston.

3. The pressure medium-driven percussion or impact apparatus claimed in claim 1, in which said piston is provided with axial channels which are open at one side of the piston and closed at the other, and in which every other channel opens toward the same side of the piston.

4. The apparatus according to claim 2, in which said piston is provided with axially extending channels which open toward the same side of the piston and said cylinder is provided with a passage adapted to pass pressure medium to a chamber on the side of the piston remote from that side where the channels are open, with the piston surface where the channels are open having a greater area than the other side of the piston.

i I! 4 I! 

1. A pressure medium-driven or impact apparatus including a cylinder, a working piston in said cylinder, means for supplying pressure to the piston, in which by supply of pressure to alternating sides of the piston the piston is caused to reciprocate, means to rotate the piston, the piston and cylinder being provided with channels which, on rotory movement of the piston relative to the cylinder, open and close the pressure medium channels, with the channels opening at the top and bottom side of the piston respectively.
 2. The pressure medium-driven percussion and impact apparatus as claimed in claim 1, in which a motor constitutes the means to rotate the piston.
 3. The pressure medium-driven percussion or impact apparatus claimed in claim 1, in which said piston is provided with axial channels which are open at one side of the piston and closed at the other, and in which every other channel opens toward the same side of the piston.
 4. The apparatus according to claim 2, in which said piston is provided with axially extending channels which open toward the same side of the piston and said cylinder is provided with a passage adapted to pass pressure medium to a chamber on the side of the piston remote from that side where the channels are open, with the piston surface where the channels are open having a greater area than the other side of the piston. 